As a technology for measuring temperatures using temperature sensors that use temperature measuring resistive elements, a three-line temperature measuring technology has been proposed. See, for example, Japanese Unexamined Patent Application Publication Nos. H09-105681 and 2012-242294.
This three-line temperature measuring technology is a temperature measuring technology for measuring a temperature through connecting, through a three-line signal cable, a temperature sensor, which houses a temperature measuring resistive element, and a temperature measuring instrument, and supplying, through these signal lines, a constant current from the temperature measuring instrument to the temperature measuring resistive element.
FIG. 6 is an example of a typical three-line temperature measuring system interconnection. As illustrated in FIG. 6, when measuring the temperature within a facility, such as an industrial plant or a building, using such a three-line temperature measuring system, a multiwire cable is used as a signal line from temperature sensors that are disposed in various locations within a processing room, to connect to multichannel input instruments and measuring instruments, and to connect to temperature measuring instruments that are disposed in a control room.
Consequently, in a case wherein the temperature measuring instruments can handle multiple channels, a total of, for example, 30 signal lines, from, for example, 10 temperature sensors, are connected to respective ports for the individual channels, provided in a centralized temperature measuring instrument. Because of this, it is necessary to confirm whether or not the signal lines are connected without error to the ports corresponding to the respective channels.
However, normally, the temperature measuring instrument is disposed in a control room, and thus, conventionally, technicians are deployed in both the control room and in the remote location wherein the temperature sensors are installed, to use testing devices, such as conductivity testers, to perform operations for checking the connections of the individual signal lines.
Because of this, there is a problem in that checking the connections for the temperature sensors requires substantial time and labor.
The present invention is to solve issues such as these, and an aspect thereof is to provide a connection checking technology able to reduce greatly the amount of time and labor required in checking the connections of the temperature sensors.